Quality Of Bone Healing Research Articles

The osteogenic and angiogenic potential of microRNA-26a delivered via a non-viral delivery peptide for bone repair

Bone-related injuries and diseases are among the most common causes of morbidity worldwide. Current bone-regenerative strategies such as auto- and allografts are invasive by nature, with adverse effects such as pain, infection and donor site morbidity. MicroRNA (miRNA) gene therapy has emerged as a promising area of research, with miRNAs capable of regulating multiple gene pathways simultaneously through the repression of post-transcriptional mRNAs. miR-26a is a key regulator of osteogenesis and has been found to be upregulated following bone injury, where it induces osteodifferentiation of mesenchymal stem cells (MSCs) and facilitates bone formation. This study demonstrates, for the first time, that the amphipathic, cell-penetrating peptide RALA can efficiently deliver miR-26a to MSCs in vitro to regulate osteogenic signalling. Transfection with miR-26a significantly increased expression of osteogenic and angiogenic markers at both gene and protein level. Using a rat calvarial defect model with a critical size defect, RALA/miR-26a NPs were delivered via an injectable, thermo-responsive Cs-g-PNIPAAm hydrogel to assess the impact on both rate and quality of bone healing. Critical defects treated with the RALA/miR-26a nanoparticles (NPs) had significantly increased bone volume and bone mineral density at 8 weeks, with increased blood vessel formation and mechanical properties. This study highlights the utility of RALA to deliver miR-26a for the purpose of bone healing within an injectable biomaterial, warranting further investigation of dose-related efficacy of the therapeutic across a range of in vivo models.

Effect of Local Tranexamic Acid on the Quality of Bone Healing in a Rat Spinal Fusion Model.

Introduction The use of the antifibrinolytic agent tranexamic acid has positive effects on bleeding control, but our knowledge is still limited regarding how fibrinolysis suppression changes the process of bone formation and the quality of bone. Because of the several side effects of systemic tranexamic acid, topical usage has been established in several procedures. This study aimed to investigate the effect of local tranexamic acid on vertebral fusion by using macroscopic, radiologic, and microscopic techniques. We also attempted to determine the safe dose range in case some doses had negative effects on fusion. Methods Twenty-eight Wistar albino rats underwent intertransverse fusion. All rats were randomized into four groups: groups treated with local tranexamic acid doses of 1 mg/kg (D1), 10 mg/kg (D10), and 100 mg/kg (D100) and the control group with no drug (D0). At the end of the eighth week, all rats were sacrificed for evaluation in terms of palpation, mammography, and histopathologic analysis. Results The manual palpation results presented with lower fusion rates in D10 and D100 groups than in the control group. Radiological examination results were significantly higher in the control group. The histopathologic examination revealed no significant differences between groups in the percent of new bone formation. Conclusions Our results showed that local administration of tranexamic acid reduced the quality and stability of fusion without a delay in bone formation. However, doses of 1 mg/kg did not reduce the stability in the palpation test. Our findings suggest that 1 mg/kg dose is a critical threshold above which tranexamic acid reduced the bone healing process of fusion and that surgeons should consider the doses of local tranexamic acid during surgery.

Repairing Rabbit Radius Bone Defects with Simvastatin Compound Biological Bone

Objective: This study aimed to investigate the feasibility of repairing rabbit radius bone defects with simvastatin compound biological bone. Methods: Simvastatin biological bone material was prepared, and osteoblasts were cultured. A total of 42 New Zealand white rabbits were randomly divided into four groups, and a bone defect with a length of 15 mm was created at the middle part of the radial shaft of both limbs in each rabbit, thereby establishing a bone defect model. The grafts in group A were biological bones of osteoblasts combined with simvastatin; the grafts in group B were biological bones of simvastatin; the grafts in group C were biological compound bones of osteoblasts; and the grafts in group D were simple biological bones. In each group, four animals were randomly sacrificed at the sixth and twelfth week after surgery, and specimens were collected for gross observation, X-ray examination, histological observation, and biomechanical testing. In each group, two animals were randomly sacrificed at the twelfth week after surgery; a three-point bending test was performed using a biomechanical testing machine, and the results were compared with those of a normal radius. Results: The X-ray and histological examinations at 6 and 12 weeks after surgery revealed that the osteogenesis ability of the simvastatin biological bone and osteoblast-simvastatin biological bone was better than that of the osteoblast biological bone and simple biological bone, which was superior in group A and group B to group C and group D. The results of the biomechanical examination revealed that the maximum stress of the normal radius was significantly higher than that of the experimental groups. Among the experimental groups, the difference between group A and group B was not statistically significant, and the maximum stress was higher in groups A and B than in groups C and D. Conclusion: Simvastatin biological bone material can promote the repair of rabbit radius defects and increase the quality of bone healing.

Compare the efficacy of healing in mandibular third-molar sockets using the combination of platelet-rich fibrin and Biograft-HT®with that of platelet-rich fibrin alone

Aim and Objectives: The aim of this prospective clinical study was to compare the efficacy of a combination of Platelet Rich Fibrin (PRF) and biograft- HT® with that of platelet rich fibrin alone in healing of impacted mandibular third molar sockets after surgical removal of the same. Objectives were to compare the post-operative pain, swelling, trismus, periodontal health distal to mandibular second molar, quality of bone healing at the mandibular third molar socket at various time intervals.Methodology : This was split mouth study where PRF and biograft- HT® was placed on one side of the third molar extraction socket and PRF alone was placed on the other side in 15 patients with bilaterally impacted 3rd molars. Results: There was no statistically significant difference seen in any of the parameters Conclusion: This study does not prove statistically significant improvement in the efficacy of combination of PRF with Biograft- HT® when compared to PRF alone. The addition of Biograft- HT® to PRF increases the cost of the treatment while PRF alone is cost effective as it is prepared with patient“s own blood. Hence, the addition of Biograft- HT® to PRF can”t be recommended based on our study alone.

Thiol-ene Hydrogels for Local Delivery of PTH for Bone Regeneration in Critical Size defects.

Neither allograft nor commercially available bone graft substitutes provide the same quality of bone healing as autograft. Incorporation of bioactive molecules like parathyroid hormone (PTH) within bone graft substitute materials may provide similar, if not better treatment options to grafting. The goal of this work was to develop a biomaterial system for the local delivery of PTH to large bone defects for promoting bone regeneration. PTH was loaded in a thiol-ene hydrogel at several concentrations and polymerized in and around an osteoconductive poly(propylene fumarate) (PPF) scaffold. PTH was shown to be bioactive when released from the hydrogel for up to 21 days. Eighty percent of the PTH was released by day 3 with the remaining 20% released by day 14. Bone healing was quantified in rat critical size femoral defects that were treated with hydrogel/PPF and 0, 1, 3, 10, or 30 µg of PTH. Although complete osseous healing was not observed in all samples in any one treatment group, all samples in the 10 µg PTH group were bridged fully by bone or a combination of bone and cartilage containing hypertrophic chondrocytes and endochondral ossification. Outcome measures indicated improved defect bridging by a combination of bony and cartilaginous tissue in the 10 μg treatment group compared with empty bone defects and defects treated with only hydrogel/PPF (i.e., without PTH). Given the tailorability of the hydrogel, future studies will investigate the effects of prolonged gradual PTH release on bone healing. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:536-544, 2020.

Efficacy of free fibula flap for reconstruction of post traumatic long bone defect: retrospective study of eighteen cases

<p class="abstract"><strong>Background: </strong>Complex and segmental bone defects are common after resection of tumors and trauma involving long bones of the extremities. Free fibula flap is commonly practiced for complex oromandibular defects and bone reconstruction after sarcoma and bone tumor excision. But post traumatic bone reconstruction of extremities with free fubula is less commonly practiced and only reserved for long segmental reconstruction or as an alternative to distraction osteogenesis. We are presenting a retrospective analysis of surgical details and outcome of 18 cases with post traumatic long bone defect reconstructed with free fibula osteocutaneous flap.</p><p class="abstract"><strong>Methods:</strong> 18 patients with post traumatic composite or segmental long bone defect which were reconstructed with free fibula osteocutaneous flap (FFOCF) between 2014 to 2018 are included in this study. Operative details, success rate, bone healing, functional outcome and complications are reviewed retrospectively.<strong></strong></p><p class="abstract"><strong>Results:</strong> Success rate of flap surgery was 17/18 (94.44%). Bone gap was 6-17 cm and Skin paddle ranged from 10 cm × 8 cm to 15 cm × 10 cm. Bone healing, weight bearing outside cast and return to daily activity period were 8-16 weeks, 10-15 months and 12-18 months respectively. Non-union, malunion and stress fracture were noted in one,one and three patients respectively.</p><p class="abstract"><strong>Conclusions:</strong> Free fibula flap is a reliable method for reconstruction of post traumatic complex and segmental long bone defects. Quality of bone healing is good enabling resuming to early weight bearing and daily activities and high success rate. Free fibula flap may be procedure of choice for reconstruction of such bony injuries with the microvascular surgical facilities.</p>

The Synergic Effect of Terpenoid and Steroidal Saponins Can Improve Bone Healing, by Promoting the Osteogenic Commitment of Adipose Mesenchymal Stem Cells: An In Vitro Study

Bone regeneration involves several biological processes that consistently impact the quality of tissue healing. An important step consists of the local recruitment and differentiation of mesenchymal stem cells that migrate in the site to regenerate from bone marrow. Mesenchymal stem cells (MSCs) may be pushed towards osteogenic commitment by specific substances, often naturally present in plants. Yunnan Baiyao (YB) is a Chinese herbal medicine, mainly working through the synergic effect of terpenoid and steroidal saponins. YB is well known for its numerous biomedical effects, including the ability to favor improved bone tissue healing. In our in vitro study, we used adipose mesenchymal stem cells (ADSCs) as a study-model: We selected samples to harvest and isolate ADSCs and investigate their viability; moreover, we performed bone-related gene expression to evaluate the differentiation of MSCs. To confirm this behavior, we analyzed alkaline phosphate activity and calcium deposition, with ADSCs cultured in basal and osteogenic media, with YB at different concentrations in the medium, and at different time-points: 7, 14 and 21 days. Our results indicate that the synergic effect of terpenoid and steroidal saponins slightly favor the late ADSCs differentiation towards the osteoblasts phenotype. In osteogenic committed cells, the treatment with the lower dose of YB promoted the up-regulation of the alkaline phosphatase gene (ALPL) at day seven and 14 (p < 0.01); at day 21, the alkaline phosphatase (ALP) activity showed a slight increase, although in basal condition it maintains low rates. We assume that such molecular synergy can promote the osteogenic commitment of adipose mesenchymal stem cells, thus improving the timing and the quality of bone healing.

Effects of an Er,Cr:YSGG Laser on Bone Regeneration in Critical-Sized Calvarial Defects of Rats Exposed to Inhalation of Cigarette Smoke.

Objective: To evaluate the effect of the Er,Cr:YSGG laser on healing of critical-sized calvarial defects (CSDs) in rats submitted to inhalation of cigarette smoke. Background: Smoking has been implicated with the delay in the bone healing after osteotomy procedures, then the use of the Er,Cr:YSGG laser for osteotomy in smokers could be an alternative to the conventional drills. Methods: One hundred animals were randomly allocated into four groups: trephine-the CSDs were made with a trephine drill in healthy rats; Er,Cr:YSGG-the CSDs were made with the Er,Cr:YSGG laser in healthy rats; Trephine-S-the CSDs were made with a trephine drill in rats exposed to cigarette smoke; and Er,Cr:YSGG-S-the CSDs were made with the Er,Cr:YSGG laser in rats exposed to cigarette smoke. The inhalation of cigarette smoke started 7 days before the surgical procedure until euthanasia (immediately, 7, 15, 30, or 60 days after the surgical procedure). A histometric analysis and a histological description were performed to evaluate (1) the residual linear lengths and bone formation in the CSDs; (2) the quality of bone healing. Results: The use of Er,Cr:YSGG laser induces more bone formation compared with the trephine in smokers; however, the closure of the CSD was only superior in the Er,Cr:YSGG-S group compared to the Trephine-S group at the 60-day period. Conclusions: The use of the Er,Cr:YSGG laser stimulated the bone repair process after osteotomy procedures in animals submitted to exposure of inhalation of cigarette smoke.

Healing Potential of Platelet Rich Fibrin in Impacted Mandibular Third Molar Extraction Sockets.

Background:Healing of both hard and soft tissues have become one of the great challenges, faced in clinical research in development of bioactive surgical additives responsible for regulating inflammation and increasing healing. Platelet-rich fibrin (PRF) represents a new step in the platelet gel therapeutic concept with simplified processing minus artificial biochemical modification.Aims and Objectives:The aim of this study is to evaluate the effectiveness of PRF on soft-tissue healing and bone tissue healing in terms of postoperative pain, postoperative swelling, soft tissue healing, and the quality of bone healing at the mandibular third molar socket.Materials and Methods:A clinical study will be done on patients reporting to the Department of Oral and Maxillofacial Surgery in Government Dental College, Srinagar, requiring disimpaction of bilateral mesioangular impacted mandibular third molars in 60 patients.Results:The present prospective clinical study evaluates the effect of PRF in healing of mandibular third molar extraction sockets. There was no difference in the age gender and type of impaction between the two groups as the mean postoperative pain score (visual analog scale) was lower for the PRF group (Group A) at all points of time when compared with the control (Group B), and this was statistically significant (P < 0.05). The mean percentage swelling was lower for the PRF group (Group A) at all points of time when compared with the control (Group B). Evaluating the effect of treatments (with or without PRF) on lamina dura score shows that in both the groups at different time periods, significant (P < 0.001) difference was observed on lamina dura score.Conclusion:The results of the present study suggest that application of autologous PRF gel has a beneficial effect on the healing of extraction sockets after third molar surgery.

Bone regeneration induced by a 3D architectured hydrogel in a rat critical-size calvarial defect.

Bone regeneration can be stimulated by implantation of biomaterials, which is especially important for larger bone defects. Here, healing potency of the porous ArcGel was evaluated in a critical-size calvarial bone defect in rats in comparison with clinical standard autologous bone and Bio-Oss® Collagen (BioOss), a bone graft material frequently used in clinics. Bone healing and metabolic processes involved were monitored longitudinally by [18F]-fluoride and [18F]-FDG μ-PET/CT 1d, 3d, 3w, 6w, and 12w post implantation. Differences in quality of bone healing were assessed by exvivo μ-CT, mechanical tests and histomorphometry. The amount of bone formed after implantation of ArcGel was comparable to autologous bone and superior to BioOss (histomorphometry). Furthermore, microarchitecture of newly formed bone was more physiological and better functional in case of ArcGel (push-out tests). [18F]-FDG uptake increased until 3d after implantation, and decreased until 12w for both ArcGel and BioOss. [18F]-fluoride uptake increased until 3w post implantation for all materials, but persisted significantly longer at higher levels for BioOss, which indicates a prolonged remodelling phase. The study demonstrates the potential of ArcGel to induce restitutio ad integrum comparable with clinical standard autologous bone and better bone regeneration in large defects compared to a commercial state-of-the-art biomaterial.

Evaluation of the effect of adipose tissue-derived stem cells on the quality of bone healing around implants

ABSTRACTPurpose/Aim: This study evaluates the efficacy of grafted adipose-derived stem cells (ADSCs) on blade-type implants in improving osseointegration in rat femurs using a low-densitybone model. Materials and Methods: After isolating and expanding ADSCs, twice-passaged cells were seeded on blade-type implants on culture plates. Osteogenic induction of grafted cells began after attaching cells to the prepared titanium surfaces and it continued for 4 days. The scaffolds were then implanted in the femurs of Wistar rats. Osteogenic differentiation of these cells was confirmed using polymerase chain reaction (PCR) and alizarin red staining ofthe mineralized extracellular matrix. After 8 weeks, histological and histomorphometric evaluations of undecalcified resin sections (bone–implant contact [BIC] % and bone mineral index [BMI]) were performed using light microscopy and scanning electron microscopy. Results: Alizarin red staining in conjunction with gene expression results confirmed osteogenic differentiation. Histomorphometric assessment using scanning electron microscopy demonstrated improved BIC% and BMI near the treated surface compared with the untreated surface. Conclusions: The complex of differentiated grafted ADSCs and extracellular matrix and the macrodesign and microdesign of the implant can improve osseointegration in low-density bone.

Role of sustained release type I collagen-vascular endothelial growth factor in promoting bone-tendon junction defect healing in rabbits

Objective To observe the effect of sustained release typeⅠ collagen-vascular endothelial growth factor (VEGF) on healing of bone-tendon junction injuries. Methods Partial patellectomy was conducted in 72 rabbits divided equally into control group, type I collagen group, and collagen type I-VEGF group. The scaffold was planted into the bone-tendon interface. Animals were sacrificed at 4, 8 and 12 weeks. New bone formation into the patella-patella tendon surface was detected using X-ray films and histological observations. Quality of bone healing was assayed using biomechanical testing. Results At postoperative 4, 8 and 12 weeks, X-ray films showed bone formation of type I collagen group [ (4.1±0.4)mm2, (12.1±0.5)mm2, (13.0±1.2)mm2 respectively] and of collagen type I-VEGF group [(3.8±0.4)mm2, (11.0±0.5)mm2, (13.1±1.0)mm2 respectively] were more than that of control group [(2.1±0.6)mm2, (4.1±0.3)mm2, (6.6±0.6)mm2 respectively](P collagen type I group > control group (P<0.05). Conclusion Sustained release type Ⅰ collagen-VEGF can accelerate early healing of bone-tendon junction injury and improve the histological and mechanical properties. Key words: Collagen type Ⅰ; Vascular endothelial growth factors; Bone-tendon junction

Three-Dimensional Printing of rhBMP-2-Loaded Scaffolds with Long-Term Delivery for Enhanced Bone Regeneration in a Rabbit Diaphyseal Defect

In this study, recombinant human bone morphogenetic protein-2 (rhBMP-2) delivery system with slow mode was successfully developed in three-dimensional (3D) printing-based polycaprolactone (PCL)/poly(lactic-co-glycolic acid) (PLGA) scaffolds for bone formation of critical-sized rabbit segmental diaphyseal defect. To control the delivery of the rhBMP-2, collagen (for long-term delivery up to 28 days) and gelatin (for shor-term delivery within a week) solutions encapsulating rhBMP-2 were dispensed into a hollow cylinderical type of PCL/PLGA scaffold. An effective dose of 5μg/mL was determined by measuring the alkaline phosphatase and osteocalcin gene expression levels of human nasal inferior turbinate-derived mesenchymal stromal cells (hTMSCs) seeded on the PCL/PLGA/collagen scaffold in vitro. However, it was found that a burst release of rhBMP-2 from the PCL/PLGA/gelatin scaffold did not induce the osteogenic differentiation of hTMSCs in vitro at an equivalent dose. In the in vivo animal experiements, microcomputed tomography and histological analyses confirmed that PCL/PLGA/collagen/rhBMP-2 scaffolds (long-term delivery mode) showed the best bone healing quality at both weeks 4 and 8 after implantation without inflammatory response. On the other hand, a large number of macrophages indicating severe inflammation provoked by burst release of rhBMP-2 were observed in the vicinity of PCL/PLGA/gelatin/rhBMP-2 (short-term delivery mode) at week 4.

P.3.d.052 Prolonged delirious state after olanzapine pamoate injection as a consequence of pro-inflammatory cytokine secretion? A case report

Bone regeneration can be stimulated by implantation of biomaterials, which is especially important for larger bone defects. Here, healing potency of the porous ArcGel was evaluated in a critical-size calvarial bone defect in rats in comparison with clinical standard autologous bone and Bio-Oss® Collagen (BioOss), a bone graft material frequently used in clinics. Bone healing and metabolic processes involved were monitored longitudinally by [18F]-fluoride and [18F]-FDG μ-PET/CT 1d, 3d, 3w, 6w, and 12w post implantation. Differences in quality of bone healing were assessed by ex vivo μ-CT, mechanical tests and histomorphometry. The amount of bone formed after implantation of ArcGel was comparable to autologous bone and superior to BioOss (histomorphometry). Furthermore, microarchitecture of newly formed bone was more physiological and better functional in case of ArcGel (push-out tests). [18F]-FDG uptake increased until 3d after implantation, and decreased until 12w for both ArcGel and BioOss. [18F]-fluoride uptake increased until 3w post implantation for all materials, but persisted significantly longer at higher levels for BioOss, which indicates a prolonged remodelling phase. The study demonstrates the potential of ArcGel to induce restitutio ad integrum comparable with clinical standard autologous bone and better bone regeneration in large defects compared to a commercial state-of-the-art biomaterial.

Immunologically restricted patients exhibit a pronounced inflammation and inadequate response to hypoxia in fracture hematomas

For patients who are known to have an impaired immune system, bone healing is often impaired. Therefore, it has been suggested that an effectively functioning immune system will have an influence on the quality of bone healing. Here, we demonstrate that cells within the fracture hematoma of immunologically restricted patients (1) exhibit a disturbed osteogenic differentiation (normal SPP1 but diminished RUNX2 expression), (2) show a strong inflammatory reaction (high IL8 and CXCR4), and (3) react on local hypoxia (high expression of HIF1A) but with inadequate target gene responses (diminished LDHA and PGK1 expression). Thus, it is already within the early inflammatory phase of fracture healing that the local gene expression in fracture hematomas of immunologically restricted patients points toward a critical regeneration.

RGD-Conjugated Copolymer Incorporated into Composite of Poly(lactide-co-glycotide) and Poly(l-lactide)-Grafted Nanohydroxyapatite for Bone Tissue Engineering

Various surface modification methods of RGD (Arg-Gly-Asp) peptides on biomaterials have been developed to improve cell adhesion. This study aimed to examine a RGD-conjugated copolymer RGD/MPEG-PLA-PBLG (RGD-copolymer) for its ability to promote bone regeneration by mixing it with the composite of poly(lactide-co-glycotide) (PLGA) and hydroxyapatite nanoparticles surface-grafted with poly(L-lactide) (g-HAP). The porous scaffolds were prepared using solvent casting/particulate leaching method and grafted to repair the rabbit radius defects after seeding with autologous bone marrow mesenchymal cells (MSCs) of rabbits. After incorporation of RGD-copolymer, there were no significant influences on scaffold's porosity and pore size. Nitrogen of RGD peptide, and calcium and phosphor of g-HAP could be exposed on the surface of the scaffold simultaneously. Although the cell viability of its leaching liquid was 92% that was lower than g-HAP/PLGA, its cell adhesion and growth of 3T3 and osteoblasts were promoted significantly. The greatest increment in cell adhesion ratios (131.2-157.1% higher than g-HAP/PLGA) was observed when its contents were 0.1-1 wt % but only at 0.5 h after cell seeding. All the defects repaired with the implants were bridged after 24 weeks postsurgery, but the RGD-copolymer contained composite had larger new bone formation and better fusion interface. The composites containing RGD-copolymer enhanced bone ingrowth but presented more woven bones than others. The combined application of RGD-copolymer and bone morphological protein 2 (BMP-2) exhibited the best bone healing quality and was recommended as an optimal strategy for the use of RGD peptides.

Analysis of the Biomechanical Properties of the Mandible after Unilateral Distraction Osteogenesis

The purpose of this study was to establish biomechanical outcomes measures to evaluate how mandibular distraction osteogenesis affects the overall quality of bone healing. Strength and functional integrity of the regenerate were determined quantitatively after unilateral mandibular distraction osteogenesis in comparison with the contralateral mandible and a partially reduced fracture. The authors hypothesized that the breaking load, yield, and stiffness of mandibular distraction osteogenesis would be significantly reduced in comparison with both the contralateral mandible and a partially reduced fracture. Sprague-Dawley rats underwent mandibular distraction osteogenesis (n = 8) or a partially reduced fracture (n = 6). Distraction was performed using 4 days' latency and then 0.3 mm every 12 hours for 8 days (5.1 mm). Partially reduced fractures had gaps fixed postoperatively at 2.1 mm. Both groups underwent 4 weeks of consolidation. The contralateral mandibles were used as controls (n = 14). Mandibles were tension tested at 0.5 mm/second to failure, and then breaking load, yield, and stiffness were determined. Mandibular distraction osteogenesis had significantly lower breaking load, yield, and stiffness than contralateral mandible, by 40, 30, and 60 percent, respectively. Breaking load was reduced in partially reduced mandibular fractures by 40 percent when compared with distraction osteogenesis. Using a standard Ilizarov protocol, the biomechanical properties of breaking load, yield, and stiffness in mandibular distraction osteogenesis were significantly lower than those in contralateral mandibles. Surprisingly, the breaking load of mandibular distraction osteogenesis was significantly greater than that of partially reduced mandibular fracture. These verifiable metrics of regenerate integrity can be used to discern optimal outcomes of mandibular distraction osteogenesis, potentially enhancing the clinical applications of this powerful technique.

Effect of exogenous transforming growth factor-beta1 on radius defects healing of experimental rabbits repaired by coralline hydroxyapatite

Objective To investigate the effect of local injection of different doses of transforming growth factor-β1 (TGF-β1) on the radius defects healing of experimental rabbits repaired by coralline hydroxyapatite (CHA). Methods Forty-eight rabbits were randomly divided into groups A (n = 16), B (n = 16) and C (n = 16). After the models of repairing defect of the radii were established, CHA was implanted. Each repairing defect of the radii was locally injected with TGFβ1 (0 for group A, 20 for group B, and 200 ng for group C) for 4 weeks. At the 2nd, 4th, 8th and 16th week after surgery the implantments were harvested. The histological changes were observe by HE staining, and the defects healing was evaluated by radiograph, biomechanical tests at the 16th week after surgery and biomechanics of the radii was measured. Results In groups A, B and C, radiograph score was 1.50, 1.91, and 4. 80), bone healing quality score was 0. 51, 0. 88, and 1.70, cortical bone remodeling and conversion score was 0. 50, 0.82, and 2.39, and new bone formation score was 0.00, 1.22, and 4.56 respectively. Those in groups B and C were higher than in group A (P < 0.05 ). Biomechanical test revealed that in groups A, B and C, maximum load (N) was 180. 14, 251.17, and 273.20, and rigid (N/mm) was 348. 83, 549. 18, and 689. 19 respectively with the difference being statistically significant among the groups (P <0. 05). Conclusion The bone defects healing of experimental rabbits repaired by CHA can be significantly promoted by local application of exogenous TGF-β1 in a dose-dependent manner. Key words: Bone defects; Biomaterial; Transforming growth factor-betal ; Repair

Effects of novel β titanium alloy with high strenghth and low elastic modulus on bone healing of osteoporotic fracture in rats

Objective To investigate the effects of a novel |3 titanium fixation with high strength and low elastic modulus on bone healing of osteoporotic fracture and its effects on stress shielding.Methods Forty female Sprague-Dawley rats were oophorectomized before establishment of femur fracture model.The fracture of left femur was stabilized by titanium alloy pin with high elastic modulus (110 Gpa,high elasticity modulus group) and the fracture of right femur by titanium alloy pin with low elastic modu-lus (30 Gpa, low elasticity modulus group).Six and 12 weeks later, the bone volume (BV) , total vol-ume (TV) and bone volume fraction (BVF) were detected by Micro-CT, and the maximum load was de-tected by biomechanical test.The effects of two titanium alloy pins on formation of bony calluses and me-chanical properties of bones were compared.Results Compared with the low elasticity modulus group, more collagen and bony callus, thicker bone trabeculae and more regular lamellar bone were found in the high elasticity modulus group.In low elasticity modulus group, TV (ROI1) was increased obvious-ly at week 6, with no statistical differences in BV (ROI 1), BV (ROI 2) and maximum load between two groups (P < 0.05).TV and BV in region ROI 1 in the low elasticity modulus group were significantly higher than that in high elasticity modulus group (P < 0.05) , while BV in region ROI 2 in low elasticity modulus group was significantly higher than that in high elasticity modulus group at week 12 postoperative-ly (P<0.05).Biomechnical test indicated that the maximum load in low elasticity modulus group was higher than that in high elasticity modulus group.Conclusions The novel B titanium alloy with high strength and low elastic modulus helps reduce effects of stress shielding, diminish bone resorption, in-crease the fibrous callus formation at the initial phase and improve the quality of bone healing at the later phase. Key words: Osteoporosis; Femoral fractures; Titanium; Rats; Elastic modulus

EVALUATION OF BONE HEALING IN FEMURS LENGTHENED VIA THE GRADUAL DISTRACTION METHOD

Treatment of leg length inequality via lengthening of the shorter extremity is an infrequent orthopedic procedure due to the requirement of special distraction devices and possible serious complications. Essential qualitative changes in operative technique development are associated with the name of G. A. Ilizarov, who paved the way for the autoregenerate gradual distraction method in the 1950s. In the years 1990 through 2006 a total of 57 patients underwent femur lengthening via gradual distraction using various types of external fixators at the Department of Pediatric Surgery, Orthopedics, and Traumatology, Faculty Hospital in Brno. The quality of bone healing was monitored and a number of parameters followed and statistically evaluated using regularly scheduled X-ray examinations. In 11 cases we had to remove the external fixator following the distraction phase, perform an osteosynthesis via a splint and fill the distraction gap via spongioplasty. The bone healing was satisfactory in the remaining 46 patients and the lengthened bone required no other fixation method. The analysis showed statistically significant deceleration in bone healing following distraction in female patients over 12 years of age, and in boys over 14 years of age. Lack of periosteal callus five weeks after surgery always signified serious problems in further healing. Severe complications were recorded in 11 cases during the distraction phase, and in 9 cases after the removal of the distraction apparatus. The aim of this report was to present the results of our study of distraction gap bone healing using the gradual lengthening approach.